Why does calling fake.Provide<T>() wipe out fakes already configured with A.CallTo()? Is this a bug?
I'm trying to understand a problem I've run into with Autofac.Extras.FakeItEasy (aka AutoFake). I have a partial solution, but I don't understand why my original code doesn't work. The original code is complicated, so I've spent some time simplifying it for the purposes of this question.
Why does this test fail? (working DotNetFiddle)
public interface IStringService { string GetString(); }
public static void ACallTo_before_Provide()
{
using (var fake = new AutoFake())
{
A.CallTo(() => fake.Resolve<IStringService>().GetString())
.Returns("Test string");
fake.Provide(new StringBuilder());
var stringService = fake.Resolve<IStringService>();
string result = stringService.GetString();
// FAILS. The result should be "Test string",
// but instead it's an empty string.
Console.WriteLine($"ACallTo_before_Provide(): result = \"{result}\"");
}
}
If I swap the order of the calls to fake.Provide<T>() and A.CallTo(), it works:
public static void Provide_before_ACallTo()
{
// Same code as above, but with the calls to
// fake.Provide<T>() and A.CallTo() swapped
using (var fake = new AutoFake())
{
fake.Provide(new StringBuilder());
A.CallTo(() => fake.Resolve<IStringService>().GetString())
.Returns("Test string");
var stringService = fake.Resolve<IStringService>();
string result = stringService.GetString();
// SUCCESS. The result is "Test string" as expected
Console.WriteLine($"Provide_before_ACallTo(): result = \"{result}\"");
}
}
I know what is happening, sort of, but I'm not sure if it's intentional behavior or if it's a bug.
What is happening is, the call to fake.Provide<T>() is causing anything configured with A.CallTo() to be lost. As long as I always call A.CallTo() after fake.Provide<T>(), everything works fine.
But I don't understand why this should be.
I can't find anything in the documentation stating that A.CallTo() cannot be called before Provide<T>().
Likewise, I can't find anything suggesting Provide<T>() cannot be used with A.CallTo().
It seems the order in which you configure unrelated dependencies shouldn't matter.
Is this a bug? Or is this the expected behavior? If this is the expected behavior, can someone explain why it works like this?
It isn't that the Fake's configuration is being changed. In the first test, Resolve is returning different Fakes each time it's called. (Check them for reference equality; I did.)
Provide creates a new scope and pushes it on a stack. The topmost scope is used by Resolve when it finds an object to return. I think this is why you're getting different Fakes in ACallTo_before_Provide.
Is this a bug? Or is this the expected behavior? If this is the expected behavior, can someone explain why it works like this?
It's not clear to me. I'm not an Autofac user, and don't understand why an additional scope is introduced by Provide. The stacked scope behaviour was introduced in PR 18. Perhaps the author can explain why.
In the meantime, if possible, I'd Provide all you need to before Resolveing, if you can manage it.
So I have a powershell script that integrates with several other external third-party EXE utilities. Each one returns its own kind of errors as well as some return non-error related output to stderr (yes badly designed I know, I didn't write these utilities). So What I'm currently doing is parsing the output of each utility and doing some keyword matching. This approach does work but I feel that as I use these scripts and utilties I'll have to add more exceptions to what the error actually is. So I need to create something that is expandable,possibly a kind of structure I can add to an external file like a module.
I was thinking of leveraging the features of a custom PSObject to get this done but I am struggling with the details. Currently my parsing routine for each utility is:
foreach($errtype in {'error','fail','exception'})
{
if($JobOut -match $errtype){ $Status = 'Failure' }
else if($JobOut -match 'Warning'){$Status = 'Warning' }
else { $Status = 'Success' }
}
So this looks pretty straightforward until I run into some utility that contain some of the keywords in $errtype within $JobOut that is not an error. So now I have to add some exceptions to the logic:
foreach($errtype in {'error','fail','exception'})
{
if($JobOut -match 'error' -and(-not($JobOut -match 'Error Log' }
elseif($JobOut -match $errtype){ $Status = 'Failure' }
else if($JobOut -match 'Warning'){$Status = 'Warning' }
else { $Status = 'Success' }
}
So as you can see this method has the potential to get out of control quickly and I would rather not start editing core code to add a new error rule every time I come across a new error.
Is there a way to maybe create a structure of errors for each utility that contains the logic for what is an error. Something that would be easy to add new rules too?
Any help with this is really appreciated.
I would think a switch would do nicely here.
It's very basic, but can be modified very easily and is highly expandable and I like that you can have an action based on the input to the switch, which could be used for logging or remediation.
Create a function that allows you to easily provide input to the switch and then maintain that function with all your error codes, or words, etc. then simply use the function where required.
TechNet Tips on Switches
TechNet Tips on Functions
I am working on a project which incorporates C code, as well as (MASM-like) assembly. I want to be able to compile it on Linux, as well as Windows, thus I am using a third-party assembler (jwasm) as follows:
QMAKE_PRE_LINK += jwasm -coff -Fo$$assembly_obj $$PWD/assembly.asm
(here, assembly_obj holds the directory I want jwasm to save the output. Oh, by the way: when using jwasm it is critical to first specify all the parameters, and only at the end the input files, otherwise it will ignore the parameters)
To make it easier for other people to compile the project, I would like to be able to check if jwasm is in their path, and if not, emit an error() telling them how to fix this. However, I am not sure if this is even possible using qmake. I have tried:
exists("jwasm") { # Always false
message("jwasm found!")
}
as well as:
packagesExist(jwasm) { # Always true
message("jwasm found!")
}
I have looked around in the qmake docs, but couldn't find any other alternatives...
Real-life case (from caff) to exemplify the short question subject:
$CONFIG{'owner'} = q{Peter Palfrader};
$CONFIG{'email'} = q{peter#palfrader.org};
$CONFIG{'keyid'} = [ qw{DE7AAF6E94C09C7F 62AF4031C82E0039} ];
$CONFIG{'keyserver'} = 'wwwkeys.de.pgp.net';
$CONFIG{'mailer-send'} = [ 'testfile' ];
Then in the code: eval `cat $config`, access %CONFIG
Provide answers that lay out the general problems, not only specific to the example.
There are many reasons to avoid configuration in code, and I go through some of them in the configuration chapter in Mastering Perl.
No configuration change should carry the risk of breaking the program. It certainly shouldn't carry the risk of breaking the compilation stage.
People shouldn't have to edit the source to get a different configuration.
People should be able to share the same application without using a common group of settings, instead re-installing the application just to change the configuration.
People should be allowed to create several different configurations and run them in batches without having to edit the source.
You should be able to test your application under different settings without changing the code.
People shouldn't have to learn how to program to be able to use your tool.
You should only loosely tie your configuration data structures to the source of the information to make later architectural changes easier.
You really want an interface instead of direct access at the application level.
I sum this up in my Mastering Perl class by telling people that the first rule of programming is to create a situation where you do less work and people leave you alone. When you put configuration in code, you spend more time dealing with installation issues and responding to breakages. Unless you like that sort of thing, give people a way to change the settings without causing you more work.
$CONFIG{'unhappy_employee'} = `rm -rf /`
One major issue with this approach is that your config is not very portable. If a functionally identical tool were built in Java, loading configuration would have to be redone. If both the Perl and the Java variation used a simple key=value layout such as:
owner = "Peter Palfrader"
email = "peter#peter#palfrader.org"
...
they could share the config.
Also, calling eval on the config file seems to open this system up to attack. What could a malicious person add to this config file if they wanted to wreak some havoc? Do you realize that ANY arbitrary code in your config file will be executed?
Another issue is that it's highly counter-intuitive (at least to me). I would expect a config file to be read by some config loader, not executed as a runnable piece of code. This isn't so serious but could confuse new developers who aren't used to it.
Finally, while it's highly unlikely that the implementation of constructs like p{...} will ever change, if they did change, this might fail to continue to function.
It's a bad idea to put configuration data in compiled code, because it can't be easily changed by the user. For scripts, just make sure it's separated entirely from the rest and document it nicely.
A reason I'm surprised no one mentioned yet is testing. When config is in the code you have to write crazy, contorted tests to be able to test safely. You can end up writing tests that duplicate the code they test which makes the tests nearly useless; mostly just testing themselves, likely to drift, and difficult to maintain.
Hand in hand with testing is deployment which was mentioned. When something is easy to test, it is going to be easy (well, easier) to deploy.
The main issue here is reusability in an environment where multiple languages are possible. If your config file is in language A, then you want to share this configuration with language B, you will have to do some rewriting.
This is even more complicated if you have more complex configurations (example the apache config files) and are trying to figure out how to handle potential differences in data structures. If you use something like JSON, YAML, etc., parsers in the language will be aware of how to map things with regards to the data structures of the language.
The one major drawback of not having them in a language, is that you lose the potential of utilizing setting config values to dynamic data.
I agree with Tim Anderson. Somebody here confuses configuration in code as configuration not being configurable. This is corrected for compiled code.
Both a perl or ruby file is read and interpreted, as is a yml file or xml file with configuration data. I choose yml because it is easier on the eye than in code, as grouping by test environment, development, staging and production, which in code would involve more .. code.
As a side note, XML contradicts the "easy on the eye" completely. I find it interesting that XML config is extensively used with compiled languages.
Reason 1. Aesthetics. While no one gets harmed by bad smell, people tend to put effort into getting rid of it.
Reason 2. Operational cost. For a team of 5 this is probably ok, but once you have developer/sysadmin separation, you must hire sysadmins who understand Perl (which is $$$), or give developers access to production system (big $$$).
And to make matters worse you won't have time (also $$$) to introduce a configuration engine when you suddenly need it.
My main problem with configuration in many small scripts I write, is that they often contain login data (username and password or auth-token) to a service I use. Then later, when the scripts gets bigger, I start versioning it and want to upload it on github.
So before every commit I need to replace my configuration with some dummy values.
$CONFIG{'user'} = 'username';
$CONFIG{'password'} = '123456';
Also you have to be careful, that those values did not eventually slip into your commit history at some point. This can get very annoying. When you went through this one or two times, you will never again try to put configuration into code.
Excuse the long code listing. Below is a handy Conf.pm module that I have used in many systems which allows you to specify different variables for different production, staging and dev environments. Then I build my programs to either accept the environment parameters on the command line, or I store this file outside of the source control tree so that never gets over written.
The AUTOLOAD provides automatic methods for variable retrieval.
# Instructions:
# use Conf;
# my $c = Conf->new("production");
# print $c->root_dir;
# print $c->log_dir;
package Conf;
use strict;
our $AUTOLOAD;
my $default_environment = "production";
my #valid_environments = qw(
development
production
);
#######################################################################################
# You might need to change this.
sub set_vars {
my ($self) = #_;
$self->{"access_token"} = 'asdafsifhefh';
if ( $self->env eq "development" ) {
$self->{"root_dir"} = "/Users/patrickcollins/Documents/workspace/SysG_perl";
$self->{"server_base"} = "http://localhost:3000";
}
elsif ($self->env eq "production" ) {
$self->{"root_dir"} = "/mnt/SysG-production/current/lib";
$self->{"server_base"} = "http://api.SysG.com";
$self->{"log_dir"} = "/mnt/SysG-production/current/log"
} else {
die "No environment defined\n";
}
#######################################################################################
# You shouldn't need to configure this.
# More dirs. Move these into the dev/prod sections if they're different per env.
my $r = $self->{'root_dir'};
my $b = $self->{'server_base'};
$self->{"working_dir"} ||= "$r/working";
$self->{"bin_dir"} ||= "$r/bin";
$self->{"log_dir"} ||= "$r/log";
# Other URLs. Move these into the dev/prod sections if they're different per env.
$self->{"new_contract_url"} = "$b/SysG-training-center/v1/contract/new";
$self->{"new_documents_url"} = "$b/SysG-training-center/v1/documents/new";
}
#######################################################################################
# Code, don't change below here.
sub new {
my ($class,$env) = #_;
my $self = {};
bless ($self,$class);
if ($env) {
$self->env($env);
} else {
$self->env($default_environment);
}
$self->set_vars;
return $self;
}
sub AUTOLOAD {
my ($self,$val) = #_;
my $type = ref ($self) || die "$self is not an object";
my $field = $AUTOLOAD;
$field =~ s/.*://;
#print "field: $field\n";
unless (exists $self->{$field} || $field =~ /DESTROY/ )
{
die "ERROR: {$field} does not exist in object/class $type\n";
}
$self->{$field} = $val if ($val);
return $self->{$field};
}
sub env {
my ($self,$in) = #_;
if ($in) {
die ("Invalid environment $in") unless (grep($in,#valid_environments));
$self->{"_env"} = $in;
}
return $self->{"_env"};
}
1;
Trying to change a few things like I had them in Xcode 3. I can't seem to get user defaults to work. These are the two changes I tried:
defaults write com.apple.Xcode XCCodeSenseFormattingOptions -dict PreExpressionSpacing ""
...which should change
if (...)
to
if(...)
and
defaults write com.apple.Xcode XCCodeSenseFormattingOptions -dict BlockSeparator "\\n"
...which should change
if(...){
}
to
if(...)
{
}
I also tried various permutations and variants like "\n" and others I found through a web search. Nothing makes XC4 behave differently. I can see the change when I use default read, but it does nothing to XC4.
BTW, I also tried something silly like:
defaults write com.apple.Xcode XCCodeSenseFormattingOptions -dict BlockSeparator "this is junk"
No changes whatsoever in XC4.
Any ideas?
Am I doing something wrong?
Thanks!